Subject: Re: bug#13448: Cannot build Emacs 24.2.92

From: Paul Eggert <[email-masked]>
Date: Tue, 15 Jan 2013 12:40:26 -0800

On 01/15/13 11:36, Glenn Morris wrote:
> So why does configure.ac contain this:
> 
>    gl_WARN_ADD([-Werror], [WERROR_CFLAGS])

That part of the Gnulib manual was out of date.
I pushed the following fix to the Gnulib manual.

---
 ChangeLog         |  7 +++++++
 doc/warnings.texi | 15 +++++++++++----
 2 files changed, 18 insertions(+), 4 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index 79defc9..1cdc89f 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,10 @@
+2013-01-15  Paul Eggert  <[email-masked]>
+
+	doc: clarify -Werror
+	* doc/warnings.texi (warnings): -Werror is not always a bad idea;
+	clarify that it's intended for developers, not for ordinary builds,
+	and mention --enable-gcc-warnings as one possible use.
+
 2013-01-15  Andoni Morales Alastruey  <[email-masked]>  (tiny change)
 
 	stdint: fix build with Android's Bionic fox x86
diff --git a/doc/warnings.texi b/doc/warnings.texi
index 40dfc20..1836c04 100644
--- a/doc/warnings.texi
+++ b/doc/warnings.texi
@@ -21,10 +21,15 @@ from gnulib), it is useful to apply different warning options to
 different directories.
 
 @item
-It allows to use @samp{-Werror} at @samp{make distcheck} time, to verify
+It lets you use @samp{-Werror} at @samp{make distcheck} time, to verify
 that on the maintainer's system, no warnings remain.  (Note that use of
 @samp{-Werror} in @code{CFLAGS} does not work in general, because it may
 break autoconfiguration.)
+
+@item
+Similarly, it lets you use @samp{-Werror} when the builder runs
+@command{configure} with an option such as
+@option{--enable-gcc-warnings}.
 @end itemize
 
 To use this module, you need the following:
@@ -49,10 +54,12 @@ and before @code{CFLAGS} in build rules emitted by Automake.  This allows
 the user to provide @code{CFLAGS} that override the @code{WARN_CFLAGS}.
 @end enumerate
 
-Note that it is a bad idea to use @samp{gl_WARN_ADD([-Werror])}.  The
+@samp{gl_WARN_ADD([-Werror])} is intended for developers, and should be
+avoided in contexts where it would affect ordinary installation builds.  The
 warnings emitted by GCC depend, to some extent, on the contents of the
 system header files, on the size and signedness of built-in types, etc.
 Use of @samp{-Werror} would cause frustration to all users on platforms
 that the maintainer has not tested before the release.  It is better if
-maintainers use @samp{-Werror} only for themselves (for example, during
-@samp{make distcheck}, as mentioned above).
+@samp{-Werror} is off by default, and is enabled only by developers.
+For example, @samp{-Werror} could affect @samp{make distcheck} or
+@samp{configure --enable-gcc-warnings} as mentioned above.
-- 
1.7.11.7